Validate Captcha in Form

I will go with Sachin's answer and try to explain a bit in detials:

I think you should modify your existing code:

1. Add a comparison between the user-entered captcha value and the captcha control's value:

if (txtCaptcha.Text != cptCaptcha.Text)
{
    lblErrorMessage.Text = "Incorrect captcha";
    return;
}

2. This code will check if the user-entered captcha value (txtCaptcha.Text) is equal to the captcha value generated by the captcha control (cptCaptcha.Text). If the values do not match, the error message "Incorrect captcha" will be displayed in the label control lblErrorMessage.

 

protected void btnLogin_Click(object sender, EventArgs e)
{
    var db = new DatabaseContext();

    var ab = db.login.Where(x => x.MobileNumber == txtMobileNumber.Text.ToString()).FirstOrDefault();

    if (applicant == null)
    {
        lblMessage.Text = "Mobile number is not registered!";
        return;
    }

    if (btnLogin.Text == "Get OTP")
    {
        Session["LoginOtp"] = "*****";
        pnl_Otp.Visible = true;
        txtMobileNumber.Enabled = false;
        btnLogin.Text = "Submit";
        txt_Otp.Focus();
    }
    else
    {
        // Captcha validation
        if (txtCaptcha.Text != cptCaptcha.Text)
        {
            lblErrorMessage.Text = "Incorrect captcha";
            return;
        }
        
        if (Session["LoginOtp"].ToString() != txt_Otp.Text)
        {
            lblMessage.Text = "Invalid OTP";
            return;
        }
        else
        {
            if (!ab.IsComplete)
            {
                Session["Username"] = applicant.MobileNumber;
                Session["Id"] = applicant.Id;
                Response.Redirect("~/index/default");
            }
            else
            {
                Session["Username"] = applicant.MobileNumber;
                Session["Id"] = applicant.Id;
                Session["usertype"] = "0";
                Session["Type"] = applicant.Type;
                Response.Redirect("~/Type/Default");
            }
        }
    }
}

The code assumes that the label control lblErrorMessage is already present on the page and is used to display the error message.
 

Have you refered this link?

https://www.c-sharpcorner.com/UploadFile/sourabh_mishra1/captcha-image-in-Asp-Net/

Naimish Makwana

 

None of your answer works for me

You can also use the ValidateCaptcha method provided by the CaptchaControl to validate the captcha text

if (!cptCaptcha.ValidateCaptcha(txtCaptcha.Text.Trim()))
{
    lblErrorMessage.Text = "Incorrect captcha";
    return;
}

Thanks

Please check below link:

https://www.c-sharpcorner.com/UploadFile/sourabh_mishra1/captcha-image-in-Asp-Net/

Hello

Naimish Makwana ,

 

implement this way but i enter correct captcha still shows "Incorrect Captcha"

 

 var db = new DatabaseContext();

            var ab= db.Logins.Where(x => x.MobileNumber == txtMobileNumber.Text.ToString()).FirstOrDefault();

            if (applicant == null)
            {
                lblMessage.Text = "Mobile number is not registered!";
                return;
            }

            if (cptCaptcha.UserValidated.ToString() != txtCaptcha.Text.ToLower())
            {
                lblErrorMessage.Text = "Incorrect captcha";
                return;
            }
            if (btnLogin.Text == "Get OTP")
            {

               
                Session["LoginOtp"] = "12121212";

                pnl_Otp.Visible = true;
                txtMobileNumber.Enabled = false;
                btnLogin.Text = "Submit";

                txt_Otp.Focus();

            }
            else
            {
                if (Session["LoginOtp"].ToString() != txt_Otp.Text)
                {
                    lblMessage.Text = "Invalid OTP";

                  return;
                }
                else
                {
                    if (!ab.IsComplete)
                    {
                        Session["Username"] = ab.MobileNumber;
                        Session["Id"] = applicant.Id;
                        Response.Redirect("~/index");
                    }
                    else
                    {
                        Session["Username"] = applicant.MobileNumber;
                        Session["Id"] = applicant.Id;
                        Session["usertype"] = "0";
                        Session["ApplicantType"] = applicant.ApplicantType;

                        Response.Redirect("~/Type/Default");

                    }

                }
            }

Hello Garima,

To validate the captcha, you can compare the user's input in the txtCaptcha textbox with the captcha text generated by the CaptchaControl. You can add condition in btnLogin_Click Click.

// Validate the captcha
    if (cptCaptcha.UserInput.ToLower() != txtCaptcha.Text.ToLower())
    {
        lblErrorMessage.Text = "Incorrect captcha";
        return;
    }

Thanks

Naimish Makwana